Method of and machine for producing gears



July 10, 1928.

1,676,419 E. WILDHABER I METHOD OF AND MACHINE FOR PRODUCING GEARS 5 Sheets-Sheet 1 Filed June 22, 1925 q My- T m H July 10, 1-928. 1,676,419

I E. WILDHABER METHOD OF AND MACHINE FOR PRODUCING GEARS Filed June 22, 1925 5 Sheets-Sheet 2 INVENTQR ERNEST WILDHABEE ATTORNJ July 10, 1928.- 1,676,419

E. WILDHABER METHOD OF AND MACHINE FOR PRODUCING GEARS Filed June 22, 1925 -5 Sheets-Sheet 5 INVENTOR ERNEST WILDHABER.

July 10, 1928;

E. WILDHABER METHOD OF AND MACHINE FOR PRODUCING GEARS Filed June 22, 1925 5 Sheets-Sheet I INVENTOR ERNE$T WILDHABEE ATTOR N FIGJW July 10, 1928. 1,676,419

E. WILDHABER METHOD OF AND MACHINE FOR PRODUCING GEARS Filed June 22, 1925 5 Shee ts-S heet- 5 INVENTOR ERNEST WILDHABEP Patented July 10, 1928.

UNITED STATES PATENT OFFICE.

ERNEST WILDHABEIQ OF ROCHESTER, NEW YORK, AS SIGNOR TO GLEASON- WORKS,

OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

METHOD OF AND MACHINE FOR PRODUCING GEARS.

Application filed .Tune 22, 1925. Serial No. 88,725.

The present invention relates to gears and particularly to gears having angularly disposed non-intersecting axes.

One object of the present mvention is to provide a method and a machlne for the generation of such gears.

A further object of this inventlon 1s to rov-ide a method for generating gears havmg angularly disposed non-intersectmg axes which will be applicable for all ratios, large as well as small. p a

A further object.-of the invention 15 to provide a method and a machine for generating gears of the type ment oned, in which the tool represents a basic helicoidal segment and in which the tool and blank are moved relatively to each other as if the blank were rolling on this basic segment.

Other objects will appear hereinafter from the specification and the claims.

In the drawings:

Figs. 1 and 2 are a plan view and side elevation respectively of a pair of gears produced according to my invention;

Figs. 3 and 4 are corresponding views of a helicoidal segment such as may be employed as 'a basic .member for' generating a gear constructed according to my invention;

Fig. 5 is a fragmentary view of a pair of helicoidal segments forming the basic members of conjugate gears constructed according to this invention;

Figs. 6 and 7 are views illustrating diagrammatically in plan and in side elevation the pitch surfaces of a pair of gears with angularly disposed non-intersecting axes;

Figs. 8 and 9 are a lan view and a side elevation respectively iilustrating diagrammatically the mesh of a gear constructed according to my invention and a basic helicoidal segment;

Fig. 10 is a view illustrating diagrammatically another aspect of my invention with particular relation to the method employed in producing the new gears;

Fig. 11 is a fragmentary side elevation showinga pair of curved tooth gears produced according to this invention;

Fig. 12 is a fragmentary sectional view showing a pair of tools 'such as mi ht be employed in producing the gears of Fig. 11;

Fig. 13 is a side elevation, partly in section, showin a pair of grinding wheels such as mig t be employed in producing curved tooth gears according to this invention' 14 is a diagrammatic view showing one of said grinding wheels in relation to the basic segment it represents;

Figs. 15 and 16 are a plan view and side elevation respectively illustrating diagrammatically the method of determining the proportions of certain ratio gears constructed according to' this invention;

Fig. 17 is a diagrammatic view illustrating a method of proportioning gears accordin to this invention where the tooth contact is outside the pitch-surface;

Fig. 18 is a plan view showing diagrammatically certain features of the typeof gears last referred to;

Figs. 19 and 20 are a lan view and side elevation respectively s owing somewhat diagrammaticallya machine for..producing gears according to this invention.

v Gears with angularly disposed non-intersecting axes have the advanta e over gears whose axes intersect that the riving member of the pair may be made of any size without altering the gear ratio. This permits of constructing gears with non-intersecting axes in which the driving member is stronger than for equal ratios where the axes .are intersecting. Arcuate gears of the type. where the axes are non-intersecting have heretofore been produced largely by an operation in which one of the gears, usually the larger member of the pair was given a toothshape of constant profile, that is, was formed according to a recess in which no rolling motion was employed, and in which the smaller member was produced by rolling the blank. relatively to a tool which repre sented a tooth of the formed gear.

The present invention aims to produce both .members of the pair according to a rolling or generating process. This method, it is believed, will produce gears which are quieter in operation and of more satisfactory construction than gears produced according to the methods heretofore employed.

One difiiculty experienced in the generation' of both members of a pair of gears arranged with axes angularly disposed and non-intersecting has been the inability to secure a theoretlcally correct basic member which might be employed in providing the movements necessary to generate gears of the type referred to regardless of ratio. In bevel gears and spur gears, a vpair of gears will correctly mesh together with full line contact when they arecapable of meshing with complementary basic members. These basic members are racks for spur ears and crown gears for bevel ears and requently these basic members are identical. The resent invention has as its basis the rovlsion of a basic member, comparable to e crown gear in bevel gearing and the rack in spur gearing, from which the tooth structure of gears with non-intersecting axes may be derived and from which the proportions of such gears regardless of ratio may be determine Figs. 1 and 2' show a pair of gears 9 and 10. having their arms 11 and 12 angularly disposed and non-intersecting. The relative motion of gears of this type, as is well known, can be considered in any instant as 'a turning motion about an instantaneous axis 13 and a simultaneous translation alon said axis 13. The pitch surfaces of suc 1 gears are hyperboloids of revolution, being produced by the movement of the instantaneous axis 13 about the respective axes 11 and 12 of the gears. The pitch surfaces will contact along the line 13.

Aside from the ar 9 there exists an infinite number of ot er ars which ma mesh with a gear 10 in suc' a way that t e line 13 is the instantaneous axis. The itch hyperboloids of all these ears wil with the pitch hyperboloid of the ear 10 along the ine 13 and at any instant t e relative'motion of thecontactin gears ma be considered as a combined sli ing and r0 ling motion about and in the direction of the axis 13. In no case will the ratioof relative sliding and turning be the same for the different ars which may mesh with the gzar 10. he instantaneous relativemotion tween the gears is therefore, a helicoidal motion having a different advance or lead for every gear combination of which-the gear 9 or 10 is a member and which has an instantaneous axis 13. The tooth contact between a' third gear and the gear 10 will depend, therefore, not merely on the location of the instantaneous axis but also on the lead or the advance per revolution of the instantaneous motion.

A consideration of the above facts has resulted in the conclusion that a third member may be interposed between two gears, such as 9 and 10, which will contact either gear along the same lines, if this third member is given not only a rotary motion, but also a translatory motion in the direction of its axis. Such a third member may be made the basic member for the production of gearsv with non-intersecting axes, which are the oretically accurate and which mesh with line contact.-

contact Such a third member is designated at 14 in Figs. 1 and 2. This third member has an axis 15 which, in the illustrated case of hyperboloidal miter gears, is preferably dis posed at rightan les to the instantaneous axis 13. This third member will have a helicoidal surface which not. only contacts with the pitch surfaces 16 and17 of the gears 9 and 10 alon the line 13, but also the instantaneous re ative motion of. this third member-with respect to either gear 9 or 10 is identical with the relative motion between these two gears, as will be more fully explained hereafter. Q l p A third member of the consideredtype is illustrated in Figs. 3 and 4. The tooth surface 19 of this member 20 may be repre sented by a suitable tool, such as the reciprocating tool 21, indicated in dotted lines in Fig. 3 and in full lines Fig. 4. A gear may be accuratel nerated if the blank is given a motion re ative tothe tool as of rolling on the basic segment represented by the tool. This relative motion will be composed not only of rotation, as in the case of bevel gears, but also oftranslation-in the direction of the axis 22 of the basic member corresponding to the lead of the pitch surface instantaneous axis.- The angles a and a included between the instantaneous axis 28 'and the axes'24 and 25 are determined in known manner by. the ratio: I

sin a N i sin a" N .'i (I) where N and N" are the tooth numbers of the res ective lgears. The distances and z" of t e respective axes of the gears from the instantaneous axis 28 are in the relation 2 tan a" (2) When the axes 24 and 25 are at right angles,

n tan tan a The above-formulas will become:

and 2.

of a pair of gears when rotated about their.

respective axes :24 and 25. in the inverse ratio of the tooth numbers N and N of the gears, will roll on each other and in addition slide in the direction of their contact line 28. At any instant the relative motion between the gears is therefore, a l'ielieoidal motion about the axis 28. The lead of this mot-ion or advance per revolution can be determined as follows I lVhen the axes 24 and 25' are at right angles:

A helicoidal member 29, shown .diagran'imatica-lly 1n Figs. 8 and 9, can be constructed and 2 will be negative when it is within the instaneous axis, as shown in Fig. 9, and will be positive when it extends beyond that axis. Usually the axes of a pair of gears are disposed at right angles as shown in Figs. 1

The formula 4 under these conditions become:

while formula 5 remains the same. From these formulas it follows, than an infinite number of helicoidal members exist which can mesh with a gear of the type referred to and which possess a relative motion of a type identical to that of the gear. Any one of these members may be employed, therefore, as a basic member from which the gear may be derived. It also follows that a gear having a pitch surface 26 capable of meshing with a third member 29, can meshwith a gear having a pitch surface 27 which itself is capable of meshing with a third member complementary to the member 29.

helicoidal members is shown in Fig. 5. They have the same axis 30 and the teeth of one member 29 will fit and completely fill the tooth spaces of the other member 31.

If, from the infinite number of helicoidal members which can mesh with a gear of the type referred to, one is chosen whose axis is so that its pitch surface will contact with the pitch surface 26 of a gear having an axis- 24, such as the gear of'Figs. 6 and 7 along the instantaneous axis 28 and so that at any instant the relative motion between the pitch' surface of the h licoidal member 29 and the pitch surface 26'of the gear is identical-with the relative ll'lOtlUl] between the pitch surfaces 26 and 27 of the gears shown in Figs. 6 and 7. In other words the relative motion between the helicoidal member 29 and the gear whose pitch surface is represented at 26 must be, at any instant, a helicoidal motion about the instantancmis axis 28, with a lead L as given by formula 3. I

The structure and position of the helicoidal'member 29 can now be'determined. Let L be the lead of the helicoidal member, 2 the distance of its axis 30 from the instantaneous axis 28, and a the angle between its axis 30 and the instantaneous axis 28, see Figs. 8 and 9. With the known i'n-ethods of kinematics the following formulas can be derived:

The hand of the helicoid'al third member, which. is right hand in Fi 1 and 2, depends ,on the-relative position of a pair of gears and may be considered in formula (5) by introducing positive and'negatlve signs. The data of a basic member having been determined, a pair of generated'gears can be readily produced.

Any tooth form may be adopted for the basic gear, and the teeth do not have to extend necessarily along the instantaneous axis 28, nor is it necessary that they extend along straight lines. .The teeth can be longitudinally curved as in the pair "of'gears, 32, 33, shown in Fig. 11. The only restriction upon the structure of gears produced according tothis invention is that the direction of the teeth be such as to permit the relative sliding inherent in this type of gear. By selecting a point on the pitch surface of one of the gears and resolving its velocity by vector analysis, one can determine. whether the teeth will permitrelative sliding between the pair or not.

At ratios of 1:1 or closely approximating 1:1, I preferably use equal 'addelnda on. both gears of a pair. At large ratiosI preferably increase the diameter of the pinion considerably and provide teeth which are Wholly outside of the pitch surface, since hypoid gears,

- surface.

unlike bevel gears, are not restricted to teeth located near the pitch surfaces. Figs. 15 to 18 illustrate one method of dimensioning a pair of hypoid gears of a ratio other than 1:1. Here the axis- 0f the helicoidal basic member 36 has been assumed at right angles to the instantaneous axis 37. The basic segment here considered is of a form such as shown in Figs. 3 and 4 containing teeth which extend in a'radial direction of the axis of the basic segment, being substantially at right angles to said axis. For ratios other than 1:1, Where the axis of the basic member is at right angles to the instantaneous axis, if the teeth of the mating gears are so constructed as to lie within the pitch surface, the pinion or smaller member of the pair will be comparatively weak and one advantage of hypoid gears over other drives will thus be lost. By constructing the gears so that their teeth lie outside of the pitch hyperboloids, however, the reqmember may uisite strength in the driving be secured. Under the condltions assumed the distance 2 of axis 35 from the instantaneous axis 37 can be determined from for mula (4") and lead of the basic member can be determined from formula (5).

As previously stated one requirement of a pair of hypoid gears is that they be capa le of relatively sliding while in mesh. The direction of relative slidin will always be at an angle to the CilIQClllOIl' of the instantaneous axis in points outside the pitch Hence the teeth of the pair of gears Whose pitch surfaces are indicated at 38 and 39 may be assumed as extending in a direction at an angle e to the instantaneous axis. 40 and 41 are the axes of the two gears-whose pitch surfaces are indicated at 38 and 39. 42 indicates the general direction. of the teeth, which can also be considered as the radial path of a cutting tool representing the basic segment shown in Figs. 3 and 4. The line 42 extends radially of'the axis 35 of the basic member.

Our problem is now to determine the lo cation. of the line 42, indicating the general direction of the teeth of the gears, relative to the instantaneous axis. The line 42 comes closest to the instantaneous axis 37 at the point 43, both lines 42 and 37 being parallel to the drawing plane of Fig. 17. The point 43 will preferably be so chosen as to be about midway of the face of the gear. The direction of relative sliding at any one point equals the direction of the tangent to a helix whose axis coincides with the instantaneous axis 37 and whose lead L is determined by equation The direction of relative sliding at the point 43 coincides with the direction 42 of the teeth, when the distance of the line 42 from the instantaneous axis 37 is such that the line 42 is a tangent to the helix just mentioned at the point 43. The

mined by:

distance of the line 42 from the instantaneous axis 37 is indicated by d in Fig. 18. This distance d evidently depends on the angle 6 shown in Fig. 17. (Z hence may be deter- 7 vto the longitudinal curvature of the teeth.

These pairs may be proportioned according to the principles disclosed in my copending application, Serial No. 29,553 filed May 11, 1925.

The teeth of the basic member, as previously stated may be either curved or straight. In either case, however, as already described, the teeth of this basic member will be of constant profile and will preferably be constantly inclined, that is. will make a constant angle, with respect to the axis of said member. Where the teeth of this memher are straight, as shown in Figs. 3 and 4, the side surfaces of the teeth will be planes; where the teeth are curved, the sides will preferably be made surfaces of revolution.

Gears capable of meshin with a basic seg m ment whose teeth are straight may be produced by reciprocating a tool, representing one or both sides of the teeth across the face of a gear blank uhilc imparting an additional relative movement between the tool and blank as if the basic segment were meshing with the gear to be produced from the blank. This relative movement will consist of a rotation of the blank and segment, rep-' resented by the tool, on their axes in timed no relation and a relative translation in'a direction of the axis of the basic segment. The tool may be reciprocated toward the axis of the basic segment or may be offset therefrom. One gear of a pair will be produced "5 by a tool representing one segment and the other gear will be produced by a tool represent-ing a complementary segment. The cutting edges of the tools may be straight or curved.

Fig. 12 shows a pair of rotary tools 48 and 49 of the face mill type such as might be em-. ployed for producing gears conjugate to complementary basic segments having longitudinally curved teeth. The coinciding axes of the basic segments are indicated at teeth have side surfaces which are portions of spherical surfaces. The adjacent toothsides of'the basic segment 20" are arts of convex and concave spherical sur aces respectively, which may have equal radii 58 and 59. Adjacent tooth surfaces have centers 60, 61, 62, 63, 64 and 65 located in two helices 66 and 67. The centers of the convex surfaces of the segment represented by the wheel 52 are located on the helix 66, while those of the concave surfaces are located on the helix 67.

The two adjacent spherical sides. of a tooth of the basic member may be represented by a wheel 52 when its axis 68 passes through the centers 63 and 64 of the tooth sides. The two adjacent spherical sides of the complementary basic member may represented by the wheel 53 when its axis 69 passes through the centers 64, 65 of the tooth sides. In this way a pair of male tools may be employed to produce conjugate gears, and with such tools it is possible to produce teeth of changing depth.

In certain cases for the sake of structural advantages in machines employed for practiring this in\'ention, a slight departure from theoretical requirements is possible. Fig. 10 illustrates the use of tools 70 and 71 representing basic segments 7 2 and 73 which are not strictly complementary. The segments have teeth arranged on helicoidal surfaces 74 and 75. The de arture from strict theory in this case is analbgous to the structural departures often made in bevel gear cutting machines.

One form of machine for practising this invention is shown in Figs. 19 and 20. In the embodiment illustrated, reciprocating tools 76 and 77 are employed representing the adjacent tooth sides of a basic segment whose teeth are straight and whose side surfaces are planes; The tools 76 and 77 are reciprocated along lines 7 8 and 79 in such manner that the points of the cuttingedges of the tools move in parallel planes, whereby the tools represent the teeth of the basic segment. The blank 80 is rotated about its axis 81 while in engagement with the tools. The tools are mounted on a cradle or support 82 which is journaled in a circular bear-' ing 83 of the frame 84 of the machine.

The tools, as already indicated, are movable relative to the support 82, their cutting edges being maintained at a constant inclinat on to a plane perpendicular to the axis 85 of the cradle, which axis represents the axis of the basic helicoidal segment. The blank spindle 86 is rotatably mounted on a slide 87 which can be adjusted vertically on the upright 88 which is itself angularly adjustable on thetable or carrier 89. The car rier 89 is adjustable and movable in a direction parallel to the axis 85 of the cradle 82. 5

During generation, the rotation of the cradle, indicated by the arrow 90, the rotation of the blank indicated by the arrow 91 and the feeding movement of the table or carrier 89, indicated by the arrow 92 are so timed that their movements impart to the tool and blank a, relative motion as of a gear rollin on the basic helicoidal segment represente by the tools. The direction of feed of the table may be either toward or from the cradle, depending on the direction of rotation of the blank and cradle.

Gearing for imparting the required motion to the various parts is indicated diagrammatically. The shaft 93 drives the worm 94 throng a pair of miter gears 95, a shaft 96, and a second pair of'miter gears 97. The worm 94 meshes with a worm wheel 98 secured to the cradle 82 and imparting motion thereto. The blank spindle 86 is driven from the shaft 93 by means of a miter gear 99, which is splined to the shaft 93, and which is journaled in a part 100 connected with the carrier 89.' The miter gear 99 meshes with a miter gear 101 secured to a shaft 102, which drives a shaft 103 through change gears 104. The shaft 103 has keyed to it a worm 105 meshing with a worm wheel 106 secured to the blank spindle 86. The blank carrier 89 is moved on the frame 84 by means of a screw 109 which is driven from the shaft 93 by means of change gears 107. The screw 109 engages a nut 108 which is secured to a carrier 89.

In operation the tools are reciprocated across the face of the blank, while the blank rotates on its axis and while the cradle slowly moves about its axis and the blank carrier is given a movement'in a direction parallel to the cradle axis. These three motions are in timed relation and generate the tooth profiles. When the cradle has been so turned that the tools 76 and 77 have been fed past the blank, two tooth sides of the blank will have been completed. The enerating movements will then be reverse and the blank withdrawn and indexed. The cyclewill then commence anew. For the sake of clearne'ss the indexing mechanism has been omitted as well as the mechanism for clapping the tools out of position on their return strokes across the face of the blank. It will be understood, however, that any suitable indexing mechanism may beemployed and any suitable clapping means. It will be understood, also, that instead of intermittently indexing the blank, the .blank may be continuously indexed as .in a bobbing operation.

The operation of the machine remains in principle the same, when instead of planing tools a face mill such as shown in Figs. 12, 13 and 14 is employed. This face mill will be rotated about its axis, while the relative generating movements remain the same as in III the machine already described. As in the as to allow for the helicoidal nature of the basic segments.

lrVhile I have illustrated my invention articularly with reference to hypoid gears aving tapered bodies, it is obvious that my invention also relates to other forms of gears with non-intersecting axes, as worm gears.

Gears which are derived from a basic tooth surface which is a lane or a surface of revolution can be readi y ground and this invention is to be understood as including grindin as well as cutting; 11 general, while I ave illustrated and described a preferred embodiment of the invention, it will be understood that the invention is capable of further modification within the limits of the disclosure and the scope of the ap nded claims. This application is inten ed to cover any variations, uses, or adaptations of my invention, following, in eneral, the principles of the invention an including such departures from the present disclosure as come within known or customary practice in the ear art and may be applied to the essential eatures hereinbefore set forth and as fall within the limits. of the appended claims.

Having thus described my invention, what I claim is:

1. The method of producing ears which consists in moving a tool across t e face of a gear blank while imparting an additional relative movement between the tool and blank as of a (gear rolling on a helicoidal segment provi ed with teeth of constant profile and constantly inclined with respect to its axis.

2. The method of producing ars which consists in moving a tool across t e face of a gear blank while imparting an additional relative movement between the tool and blank as of a gear rolling on a helicoidal segment provided with teeth whose side surv faces are planes.

3. The method of producing gears which consists in moving a tool across the face of a gear blank so that points of its cutting edge move along lines lying in parallel planes, rotating the blank about its axis while in engagement with the tool and im parting a relative helicoidal movement between the tool and blank about an axis offset from the blank axis.

4. The method of producing gears which and blank about an axis offset from the blank axis in timed relation with the "blank rotation and simultaneously feeding the blank and tool relatively to each other in a direction parallel to the axis about which the last named movement takes place.

5. The method of producing gears which consists in moving a tool across the face of a gear blank so that points of its cutting edge move along lines lying in parallel planes, rotating the blank on its axis while in engagement with the tool and imparting an additional relative movement between the tool and blank. about an axis offset from the blank axis and simultaneously feeding the blank and tool relatively to each other in a direction at an angle to'the axis of rotation of the blank. a

6. The method of producing gears adapted to mesh interchangeably with a basic helicoidal segment which consists in movin a tool across the faceof a gear blank so t at oints in its cutting edge move along lines ying in parallel planes, while imparting an additional relative movement between tool and blank as of a gear rolling on said basic se ment.

The method of producing gears which consists in moving a tool'across the face of a gear blank, rotating the blank on its axis and imparting a relative helicoidal movement between the tool and blank about an axis offset from the axis of the blank while maintaining the cutting edge of the tool at a constant inclination to a plane perpendicular to said last named axis.

8. The method of producing gears which consists'in moving a tool in a straight line across the face of a gear blank, rotating the blank on. its axis and imparting an additional relative movement between the tool and blank about an axis offset from the axis of the blank while maintaining the cutting edge of the tool at a constant inclination to a plane perpendicular to said last named axis and feeding the tool and blank relatively to each other in a direction parallel to said last named axis. 7

9. The method of producing gears which consists in moving a tool across the face of a gear blank rotating the blank on its axis while in*engagement with the tool and si multaneously moving the tool about an axis ofiset from the axis of the blank in timed relation to the blank rotation while imparting a relative feeding movement between tool and blank in a direction parallel to the last named axis. I

10. The method of completely generating a gear which consists in moving a tool across the face of a gear blank, while rotating the blank on its axis, simultaneously imparting an additional relative movement between the, tool and blank about an axis offset from the blank axis and feeding the tool and blank relatively to each other in a direction at an angle to the blank axis.

11. The method of producing gears which consists in moving a tool across the face of a gear blank, rotating the blank on its axis while in engagement with the tool, moving the tool at a constant rate about an axis offset from the axis of the blank and simultaneously feeding the tool and blank relatively to each other in a direction parallel to the last named axis.

12. In a machine for producing gears, a

' tool, means for moving the tool across the face of a gear blank so that oints of its cutting edge move along lines ying in parallel planes, means for rotating the blank on its axis while in engagement with the tool and means for simultaneously imparting an additional relative movement between the tool and blank about an axis offset from the blank axis.

13. In a machine for producing gears, a tool, means for moving the tool across the face of a gear blank so that points of its cuttingedge move along lines lying in parallel planes, means for rotating the blank on its axis While in engagement with the tool and means for simultaneously imparting an additional relative movement between the tool and blank. about an axis offset from the blank axis in timed relation with the blank rotation.

14. In a machine for producing-gears, a tool, means for moving the tool across the face of a gear blank so that points of its cutting edge move along lines lying in par-- allel planes, means for rotating the blank on its axis while in engagement with the tool, means for simultaneously imparting an additional relative movement beween the tool and blank about an axis offset from the blank axis and means for imparting a relative feeding movement between the tool and blank in a direction parallel to the axis about which the last named movement takes place.

15. In a machine for producing gears. a tool. means for moving the tool across the face of a gear blank and means for impart-- ing an additional relative movement between the tool and blank' as of a gear rolling on a helicoidal segment provided with teeth of constant profile whose side surfaces.

are constantly inclined withrespect to the axis of said segment blank,

blank spindle journaled in 16. In a machine for producing gears adapted to mesh interchangeably with a basic helicoidal segment, a tool, a support for a gear blank, means for moving the tool across the face of the blank so that points of its cuttin edge move along lines lying in parallel p anes and means for imparting an additional relative movement between the tool and blank as of a gear rolling on said basic s gment.

17. n a machine for producing gears, a tool, means for moving the tool across the face of a gear blank, means for rotating the blank on its axis while in engagement with the tool and means for simultaneously mov-.

ing the tool about an axis offset from the blank axis in timed relation with the blank rotation.

18. In a machine for producing gears, a tool, a support for a gear blank rotatable on an axis coinciding with the axis of the means for moving the tool across the face of the gear blank, means for rotating the blank support, means for simultaneously moving the tool about an axis offset from the axis of the blank in timed relation with the blank rotation and means for simultaneously imparting a relative feeding movement between the tool and blank support in a direction at an angle to the axis of the blank.

19. In a machine for producing gears, a frame provided with a circular bearing, a tool support journaled in said bearing, a tool mounted on said support for movement relative to said support, a blank carrier slidably mounted on the frame, a blank spindle rotatably mounted on the carrier, means for moving the tool across the face of the blank mounted on said splndle and means for s1- multaneously and in timed relation moving the tool support in its bearing, rotating the blank spindle on its axis, and moving the blank carrier on the frame.

20. In a machine for producing gears, a frame, a support oscillatably mounted on the frame, a support slidably mounted on 21. In a machine for producing gears, a.

a tool support rotatably mounted on said frame, a blank carrier slidably mounted on said frame, a tool mounted on said tool support for movement relative thereto, a

said blank supframe,

port having an axis of rotation coinciding with the axisof the blank carried thereby and offset from the axis of rotation of the tool support, means for moving the tool relatively to its support across the face of the gear blank, means for rotating the blank spindle on its axis and means for simultane ously and in timed relation therewith moving the tool support about its axis and actuating the blank carrier on the frame.

22. The method of producing a gear which consists in moving a tool across the face of a gear blank while imparting a relative rolling movement between the tool and blank in the manner of a gear rolling on a helicoidal segment whose side tooth surfaces are of .constant profile and such as mi ht be generated by a line, the points of which move in parallel planes.

23. The method of producing a gear which consists in. moving a tool across the face of a gear blank while imparting a relative rolling movement between the tool and blank in the manner of a geamrolling on a helicoida'l segment whose side to purfaces are of straight profile and such as might be Y frame,

generated by a line, ,the points of which move in parallel planes:

24. The method of producing a gear which consists in moving a tool across the face of a gear blank while imparting a relative rollin movement between the tool and blank in the manner of a'gear rolling on a helicoidal segment having teeth which are of constant profile and which extend radially of its axis. I

25. In a machine for producing gears, a frame. a tool sup ort, a tool carried thereby, a rotatable blank support, a cradle, journaled in theframe, upon which one of said supports is mounted, means for positioning the blank support with its axis offset from the axis of the cradle, means for moving the tool across the face of the blank, means for imparting a rotary movement to the blank support and for simultaneously imparting movement to the cradle, and means for simultaneously'imparting a further relative movement between the tool and blank in adirection parallel to the cradle axis. 26. In. a machine for producing gears, a tool, a blank support, means for moving the tool across the face of the blank and means for simultaneously imparting an additional relative movement between the tool and blank in the manner of a gear rolling on a helicoidal segment whose side tooth surfaces are of constant profile and such as might be generated by a line, the points of which move in parallel.planes.

27. In a machine for .frame, a tool support, a tool carrie producing gears, a a tool support, a tool carried thereby,

arotatable blank support, a carrier, upon I port on its axis and means for simultane-- ously imparting movementto the carrier on its axis. 1

28. In a machine for producing ears, 0.

5 thereby, a rotatable blank support, a carrier, upon which the tool support is mounted, journalled in said frame, means for positioning the blank support with its axis offset from the axis of said carrier, means for moving the tool across the face of the blank, means for rotating the blank support on its axis and means for simultaneously imparting movement to the carrier on its axis.

29. The method of producing a gear which consists in cutting its side tooth surfaces by reciprocating a tool in a straight path across the face of a gear blank, while rotating the blank on its axis and simultaneouslyv imparting a relative rotational movement between the tool and blank about an axis intersecting the tool path and offset from the blank axis tool mounted on one of said supports for movement radially of the axis of the first su port, a blank spindle journaled in the ot er su port, means for positioning the blank spindle with its axis offset from the axis of the first support, means for reciprocating the tool, means for rotating the blank, and means for simultaneously and in timed relation rotating the first support on itsvaxis and feeding the second support in a direction parallel to the last named axis.

31. In a machine for producing gears, a blank spindle, a tool, means for rotating the blank spindle on its axis, means for simultaneously imparting a relative rotational movement between-the tool and blank on an axis offset from the blank axis, means for imparting a relative feed movement in the direction of said offset axis, and means for reciprocating the tool across the face of the blank in a line extending radially of said 

